1. Field of the Invention
The present invention relates to a seal structure between two members and more particularly to a seal structure comprised of a recessed sections of first member and protruding sections of second member.
2. Prior Art
FIG. 9 shows a conventional example of a seal structure between two components connected by screws. In this seal structure, a first member 10 and a second member 12 are combined with the back surface of the second member 12 fitted against the front surface of the first member 10. Then, these two members 10 and 12 are formed into a single unit using a screw 14.
More specifically, in the front surface of the first member 10, a recessed section 16 is formed; and a protruding section 18 that has a shape fitting into the recessed section 16 of the first member 10 is formed in the back surface of the second member 12. The protruding section 18 is inserted into the recessed section 16. Moreover, the screw 14 is screwed into a screw hole 22 formed in the tip end of the protruding section 18 from an opening 20 formed in the bottom of the recessed section 16. By way of this screw 14, the second member 12 is pulled against the first member 10, and these two members are formed into a single unit so that the front surface of the first member 10 and the back surface of the second member 12 are in contact with each other.
In the above structure, when an airtight or watertight seal is to be formed between region A of the front surface of the second member 12 and region B of the back surface of the first member 10, a seal is employed. The seal is provided between the back surface of the second member 12 and the front surface of the first member 10 inside the recessed section 16. In this case, the external diameter of the protruding section 18 is made smaller than the internal diameter of the recessed section 16, so that there is a gap between the outer circumferential surface of the protruding section 18 and the inner circumferential surface of the recessed section 16. An O-ring 24 that is thick enough to fill this gap is mounted on the protruding section 18, and the protruding section 18 is inserted into the recessed section 16. A seal is thus formed by the O-ring 24.
However, in the above-described conventional seal structure, the O-ring 24 needs to be mounted on the protruding section 18. As a result, the overall amount of work required for obtaining the sealing increases. Furthermore, even after the O-ring 24 is mounted on the protruding section 18, the O-ring 24 is anchored merely on the protruding section 18 as a result of being tightened against the protruding section 18 by its own radial contractive force. Accordingly, if an external force that causes the O-ring 24 to slide along the outer circumferential surface of the protruding section 18 against the radial contractive force is applied, the O-ring 24 would slip off of the protruding section 18.
There are various kinds of household electrical appliances (products consisting of resin molded articles, electric shavers, driers, electric hair-trimmers, electric toothbrushes, information terminals such as portable telephones, etc.) that are comprised of two elements combined as in the above-described first and second members 10 and 12. In one example, a covering layer made of an elastomer (e.g., a cosmetic layer) is disposed on the front surface of one member to form an outer panel, and this outer panel is attached to the front surface of another member that is a main body casing of an electrical product.
In this household electrical product, at least the member that is the outer panel is made from a resin molding in order to reduce the weight of the product. When a covering layer is formed on the surface of the outer panel, the covering layer of an elastomer is integrally formed on the surface of this outer panel by insert molding method.
The elastomer that forms the covering layer is a polymer that has rubber-like elasticity at ordinary temperatures, and it includes natural rubbers, any of various types of synthetic rubbers, reclaimed rubbers, acrylic resins, etc. The inventor of the present application believed that it would be possible to use such an elastomer as a sealing material instead of O-rings 24.
Accordingly, the object of the present invention is to solve the above-described prior art problems.
More specifically, the object of the present invention is to provide a seal structure in which an elastomer that constitutes a covering layer formed on the surface of a constituting element of, for instance, an electric appliances, used as a sealing material, thus eliminating the use of O-rings.
The above object is accomplished by a unique-structure of the present invention for a seal structure between a first member and a second member that are assembled into a single unit so that a protruding section formed in the second member that has a covering layer of an elastomer formed on its front surface is fitted into a recessed section of the first member; and in the unique structure of the present invention, a through-hole that passes through the second member is formed in a position that corresponds to the circumferential edge of the protruding section of the second member, and a tubular covering layer of the elastomer is formed on the outer circumferences of the protruding section so that the tubular cover layer is continuous with the covering layer of the front surface of the second member via the through-hole.
With the structure above, the covering layer that covers the outer circumference of the protruding section contacts tightly to both the outer circumferential surface of the protruding section and the inner circumferential surface of the recessed section when the protruding section is inserted into the recessed section. Consequently, the space between the protruding section and the recessed sections is sealed. Furthermore, when the covering layer is formed on the surface of the second member by insert molding, the covering layer is simultaneously formed on the outer circumference of the protruding section by allowing the elastomer to flow in to around the outer circumference of the protruding section that is on the back surface of the second member via the through-hole. Accordingly, O-rings become unnecessary, and the number of components required is reduced. Also, the work required to attach such components can be eliminated, and the overall amount of work to assemble two members into a single body is reduced.
In the above structure, the external diameter of the covering layer that is formed on the outer circumference of the protruding section is set so as to be larger than the internal diameter of the recessed section.
In the present invention, the covering layer that covers the outer circumference of the protruding section can be formed so as to protrude from the tip end of the protruding section. By way of this structure, even if the external diameter of the covering layer that cover the outer circumference of the protruding section is slightly smaller than the internal diameter of the recessed section, the portion of the covering layer that protrudes from the tip end of the protruding section forms a seal between the protruding section and recessed section since it contacts the bottom of the recessed section.
Furthermore, the first member can be a part of the main body casing of an electric shaver, and the second member can be a part of the outer panel of such a shaver. In this structure, the outer panel is fitted to the main body casing, thus providing a waterproof electric shaver or a waterproof electric shaver body.